1. Technical Field
The invention relates to a trailer for transporting large bulky machinery and more specifically to a trailer for transporting agricultural combine harvesters.
2. Background Art
Machinery has in some cases been miniaturized over the years. In other cases it has been increased in size to provide increased capacity. The increase in size to increase capacity has been especially common in agricultural machinery. As the number of people engaged in farming has decreased, each farmer has had to produce more and more food to feed the population. Tractors have had increases in pulling power with little change in the physical size and in some cases with a decrease in physical size. Agricultural tillage tools and harvesting equipment have had drastic increases in size and capacity over the years. To increase the quantity of crop material harvested in an hour it is usually necessary to increase the physical size of machines for harvesting and treating crop material.
One of the most striking examples of the changes of agricultural machinery capacity and size is the agricultural combine harvesters for harvesting and threshing grain crops. The capacity of individual combine harvesters has increased by a factor of four or more in the last 20 to 30 years while the weight has more than doubled. Combine harvesters currently manufactured in North America, with a harvesting header or table removed, are about thirteen feet wide, over twelve feet high, more than twenty feet long and weigh over 23,000 pounds with the grain tank empty.
The need to transport combine harvesters from one field to another has increased as capacity has increased. Their capacity and cost has exceeded what many farmers can justify in view of government policy to have low food prices. Individual farmers also find it difficult or impossible to employ the number of people required to staff a harvesting operation. As a result many farmers have their crops harvested by professional harvesters that travel from farm to farm.
The transportation infrastructure has not kept up with the need to move large harvesting machines efficiently and safely. Railroad transportation systems have not been able to adapt to the changing requirements. Road network have been changed to meet the new requirements by increasing road widths, bridge widths and overhead clearances. However, increased regulation concerning weights and weight distribution have not adapted to changing demands. The weight limitations for truck axles have remained virtually unchanged. It has been nearly impossible to move two combine harvester separators on one trailer without exceeding the maximum weight limitations on the rear trailer axles.